1. Field of the Invention
The present invention relates to a method of processing an inner surface of a bearing having a cylindrical shape which bearing includes a resin layer composed mainly of synthetic resin on the innermost side thereof.
2. Description of the Prior Art
Conventionally, there has been a cylindrical shaped bearing including a resin layer provided on an inner surface thereof, which bearing is fabricated by a method including the steps of providing a porous sintered body on a backing metal of a flat plate shape for example, providing the resin layer on the porous sintered body by impregnating and coating the porous sintered body with synthetic resin, for example, with thermosetting resin so that a flat plate material is obtained, cutting the flat plate material to have a predetermined dimension, and subjecting the cut flat plate material to bending working (or winding working) such that the cylindrical shaped bearing has the resin layer on the inner surface thereof.
When producing a bearing having such a configuration, there has been the case that a surface of the resin layer becomes rough, or dimensional accuracy of an inner diameter of the bearing deteriorates, due to a difference between a contraction coefficient of the resin forming the resin layer and that of the porous sintered body and the like. Also, when performing the bending working such that the resin layer is located on the inner side, the thickness of the resin layer is increased, which results in an uneven thickness of the resin layer. In order to solve these problems, there has been the case that it is necessary to process the inner surface of the bearing.
In the case of a bearing used in a compressor for an air conditioner for example, high accuracy is required for an inner diameter of the bearing to enhance the compression capacity. In such a case, by applying machine work such as cutting or polishing, the roughness of the inner surface of the bearing is improved, and the accuracy of the inner diameter of the bearing is secured.
On the other hand, in the case of a bearing configured such that the above-mentioned resin layer includes fibers, there is known a method of inserting a bar shaped mandrel into an inner diameter portion of the bearing after cutting the resin layer of the inner surface of the bearing, so as to press scuffing of the fibers generated by the cutting with a peripheral surface of the mandrel (see JP-A-2001-311429, especially claims 1 and 3, paragraphs [0004] and [0006], and FIGS. 1 and 4 therein). JP-A-2001-311429 also discloses a method of inserting a heated mandrel into the inner diameter portion of the bearing after cutting the resin layer of the inner surface of the bearing.